I like to keep myself surrounded with a few close friends who get on well with me. That way, when I have to interact with strangers, I have
lackeys extroverts to do the talking initially and diffuse the tension.
For that reason, I think the characters I'd like the best would be Pohatu, Lewa, and Gali, the friendliest of the characters we've seen. I like to think I'd get on well with Onua, too, but not for the above reasons, of course. Takanuva seems a little too excitable for my liking, and Tahu and Kopaka are too serious.
(I'm keeping my answer limited to the original seven Toa, because everyone beyond that basically got very little characterization.)
Playing more loosely, I would really enjoy the Piraka's company if I didn't have to worry about the constant backstabbing and brawling. With the exception of Zaktan, they are the funniest characters in all of BIONICLE, no contest. (Zaktan, meanwhile, is one of the coolest characters, but probably not a great guy to be around.)